The present invention generally relates to internal combustion engines and, more particularly, to a system and method for derating an engine to encourage servicing of a vehicle.
It is well established that vehicles having internal combustion engines require both periodic routine maintenance and non-routine maintenance, particularly with respect to the internal combustion engine. Many elements of an internal combustion engine are designed to receive preventative maintenance at preestablished times or to require servicing as the performance of various components is compromised through use. For example, and not by way of limitation, many vehicles include internal combustion engines which have a particulate filter disposed in-line with the exhaust system. One such prior art internal combustion engine is illustrated schematically in FIG. 1.
As is known in the art, an internal combustion engine 10 includes an intake manifold 12 for the induction of air to be mixed with the fuel supply (not shown). The engine 10 also includes an exhaust manifold 14 for carrying away exhaust gases produced by the combustion process. Some engines, such as the one illustrated in FIG. 1, include a turbocharger 16, which utilizes a finned wheel 18 driven by exhaust gases to rotate a coupled compressor wheel 20 that is operative to compress fresh intake air at the inlet 22 in order to provide a denser air supply to the intake manifold 12. The incorporation of a turbocharger 16 is not necessary for practice of the present invention.
The engine 10 may have a particulate filter 24 positioned in-line with the exhaust system, particularly if the engine 10 is a diesel engine. The function of the particulate filter is to trap the majority of solid particulate matter produced by the combustion process within the engine 10 before the exhaust gases reach other sensitive exhaust aftertreatment components (such as a catalytic converter) downstream 26 from the particulate filter 24 or before the exhaust gases are simply exhausted to the environment.
It is well known in the art that a particulate filter 24 will eventually become partially clogged by the particulate matter that it is extracting from the exhaust gas. Such partial clogging creates a restriction to the flow of exhaust gases through the particulate filter 24, thereby increasing the pressure of the exhaust gases upstream from the particulate filter 24. This increase in exhaust gas pressure is known as backpressure. Increases in backpressure actually produce work in opposition to the productive work being performed by the engine 10, thereby lowering its performance. Because of this, it is desirable to clean or replace the particulate filter 24 after it has achieved some level of particulate blockage. In the prior art system shown in FIG. 1, the backpressure is measured by a pressure sensor 28 and the signal is applied as an input to an electronic control module (ECM) 30, which functions as a control system managing performance of the engine 10. The software within ECM 30 is designed to evaluate the backpressure sensed by pressure sensor 28 in comparison to two thresholds. When the backpressure exceeds a first threshold, the ECM 30 activates a first output in order to illuminate a yellow warning light 32 that is visible to the driver. When the backpressure sensed by sensor 28 exceeds a second, higher level, ECM 30 activates a second output in order to illuminate a red warning light 34, also visible to the driver. It will be understood that sensor 28 can be a transducer or simply a threshold switch.
Ideally, upon observation of the yellow warning light 32, the driver of the vehicle will arrange for service of the particulate filter 24 at the next available opportunity. Certainly by the time the red warning light 34 is illuminated, service of the particulate filter 24 should be a high priority for the driver of the vehicle. Unfortunately, many engines 10, particularly heavy duty diesel engines, are installed in vehicles which are being driven by persons other than those who own the vehicles. Such persons often do not have maintenance of the vehicle as their highest priority, particularly when the operator of the vehicle receives compensation in proportion to the amount of time that the vehicle is being operated.
The above-illustrated problem in inducing a vehicle operator to perform service of the particulate filter 24 is merely illustrative of a more widespread problem in encouraging vehicle operators to perform any necessary service that is not severely impacting the operability of the vehicle. In many cases, delaying such service can cause further damage to the vehicle, greatly increasing the cost of service. There is therefore a need in the prior art for a system which will provide an increased incentive to the operator of the vehicle to perform necessary service to the vehicle. The present invention is directed toward meeting this need.
In one embodiment of the present invention, a system is disclosed for monitoring the backpressure produced by a particulate filter of an internal combustion engine. When the backpressure of the engine exceeds a predetermined threshold, indicating that the particulate filter should be serviced soon, an input to the electronic control module (ECM) indicating the intake manifold boost pressure is shunted to ground, thereby giving the ECM a false indication that no boost is being applied to the intake manifold. This will cause the ECM, according to its normal engine management software, to derate the engine performance to a xe2x80x9cno air torque settingxe2x80x9d, thereby limiting the amount of torque that the vehicle operator can extract from the engine. This decreased performance of the engine provides a very high incentive to the vehicle operator to bring the vehicle in for servicing, at which point the particulate filter can be serviced. Upon servicing of the particulate filter, the backpressure threshold condition is no longer met, the input line to the ECM from the boost pressure sensor is no longer shunted to ground, and engine operation is returned to normal. Other embodiments of the present invention contemplate the use of engine performance derating in order to provide the vehicle operator with an incentive to have any sensed engine or vehicle condition serviced.
In one form of the present invention, a method for derating an engine to encourage servicing of a particulate filter in an exhaust system of the engine is disclosed, comprising the steps of a) sensing an exhaust backpressure upstream of the particulate filter; b) comparing the backpressure to a first threshold value; c) illuminating a first warning light visible to an operator of the engine if the backpressure exceeds the first threshold value; d) comparing the backpressure to a second threshold value; e) illuminating a second warning light visible to the operator if the backpressure exceeds the second threshold value; f) comparing the backpressure to a third threshold value; and g) derating a performance characteristic of the engine if the backpressure exceeds the third threshold value.
In another form of the embodiment, a method for derating an engine to encourage servicing of a particulate filter in an exhaust system of the engine is disclosed, comprising the steps of a) sensing an exhaust backpressure upstream of the particulate filter; b) comparing the backpressure to a threshold value; and c) derating a performance characteristic of the engine if the backpressure exceeds the threshold value.
In yet another form of the embodiment, a method for derating an engine to encourage servicing of a vehicle into which the engine is installed is disclosed, comprising the steps of a) sensing a condition of the vehicle; b) comparing the condition to a threshold value, wherein servicing of the vehicle is warranted if the condition exceeds the threshold value; and c) derating a performance characteristic of the engine if the condition exceeds the threshold value.
In another form of the embodiment, a system for derating an engine to encourage servicing of a particulate filing in an exhaust system of the engine is disclosed, comprising a sensor operable to sense an exhaust backpressure upstream of the particulate filter, the sensor having a sensor output; and an electronic control module having a first electronic control module input coupled to the sensor output and having an electronic control module output coupled to the engine; wherein the electronic control module is operative to change a state of the electronic control module output if the sensor output exceeds a predetermined level; and wherein changing the state of the electronic control module output is operative to derate a performance characteristic of the engine.